Voters in the District of Columbia and Maryland will cast ballots Tuesday in primary elections for city, county, state and congressional offices. The winners selected tomorrow will be party nominees for the general election on Nov. 2.

D.C. voters will also decide on an initiative requiring mandatory minimum sentencing for certain violent or drug-related crimes, and Marylanders will choose nonpartisan candidates for school board.

In the District, there will be party primaries for mayor, City Council chairman, council seats in Wards 1, 3, 5 and 6, two at-large council seats, and for the office of non-voting delegate to Congress.

Only voters registered as Democrats, Republicans or D.C. Statehood Party members will be allowed to vote in the primaries for those offices. However, all registered voters, including independents, will be able to vote on the mandatory minimum sentencing initiative, which is officially called Initiative No. 9.

In Maryland, there are Democratic and Republican primaries for governor and lieutenant governor, the U.S. Senate, Congress, the state legislature, county executive and county council. Republicans will also choose a nominee for state comptroller.

In Prince George's and Montgomery counties, voters must also choose school board candidates. Winners of the school board races will face a runoff in November.

Prince George's residents also must vote on nominees for clerk of circuit court and sheriff. In Montgomery County, voters will choose judges for the 6th judicial circuit, clerk of circuit court, sheriff and state's attorney.

In Maryland, all registered voters can vote for school board candidates, but only registered Democrats or Republicans are eligible to vote in the party primaries. They will find on their ballots names of candidates seeking seats on county Republican and Democratic central committees.

Polls in the District of Columbia, Prince George's and Montgomery counties will be open Tuesday from 7 a.m. to 8 p.m.

For additional information on voting in Washington call the Board of Elections and Ethics at 347-4509; in Prince George's call the Board of Elections at 952-3270; in Montgomery at 279-1507.